(WARNING: This article contains potential spoilers for Peter Capaldi's final episode of Doctor Who, which airs this Christmas. Please read at your own risk.)

Series 10 of Doctor Who is officially underway. Three weeks in, and it's proving to be an absolute blast. Fans know Series 10 of #DoctorWho will be #PeterCapaldi's final run as the Doctor before he departs this Christmas, alongside current showrunner, Steven Moffat.

Christmas is a time for happiness and spending time with the family, right? You don't expect death, unless it's Doctor Who. According to reports, Peter Capaldi has already filmed his regeneration scene as the Doctor, and all he has left to do is film the rest of the annual festive special. Filming for his last episode will be taking place in July, potentially alongside David Bradley, who is rumored to be portraying the First Doctor in what is said to be a tale of redemption and hope. However, judging by recent comments online, a well-known companion is about to storm back onto our screens, but who?

She's A Fan Favorite, But At the Same Time She Isn't

'Doctor Who' [Credit: BBC]

That's right, Clara Oswald (played by Jenna Coleman) could make an epic comeback this Christmas to witness Peter Capaldi regenerate. Clara was killed off in Episode 10 of Series 9, before being resurrected in the series finale. With Clara traveling through time and space in her own TARDIS, she could be about to make an unscheduled stop to visit the Doctor for one last goodbye.

Twitter claims that Eddie's Diner has been booked by BBC Doctor Who for two days of filming. Hardcore fans know that Eddie's Diner is, in fact, Clara and Ashildr's (Maisie Williams) TARDIS in disguise. So, this can only mean one thing — the return of Clara Oswald and Ashildr. The tweet read:

"Eddie's Diner got booked by the BBC for filming in July for 2 days. Given the fact that my friend asked the owner about Doctor Who, ad did his Doctor Who photos in the Diner, I'm sure that he means Doctor Who. I only got the date of July... No specific date was given."

When asked, exact filming days were not given out. However, the people approaching Eddie's Diner were told that filming will be taking place in July. It has been previously reported that Peter Capaldi's last episode will be filmed in July, so Jenna Coleman's return is even more likely.

Is It Just A Cameo Or An Entire Episode?

'Doctor Who' [Credit: BBC]

At this point in time, we have to wait for the official confirmation from the actress herself or the #BBC. If she's in the full episode alongside Capaldi (and possibly David Bradley), then that's likely to cause a massive uproar among fans of the Doctor Who universe. However, some fans will be seeing this as the best Christmas present ever.

But, if it's a cameo, is Steven Moffat doing what Russell T. Davies did when he left the show? In 2010 the Tenth Doctor (played by #DavidTennant) went to visit all of his companions one last time before he regenerated into the next incarnation.

Final Thoughts

For now, we just have to wait and see. In the mean time, we have Series 10 to continue enjoying, with newcomer companion Bill Potts (played by Pearl Mackie). Doctor Who airs every Saturday on BBC One and BBC America until July 2017. Check out the trailer below, and see if it meets your expectations: